Illustrative embodiments of the invention relate generally to ergonomic equipment for relieving repetitive workplace stresses, and more particularly to relieving cumulative stresses from work in which the unsupported, human arm, wrist and hand are engaged in protracted reaching.
Many scientific, medical and industrial tasks involve the hand deployment of lightweight objects or instruments, which must be held aloft and manipulated in space for extended periods of time. The act of ‘pipetting,’ (dispensing small amounts of liquid into numerous receptacles), for example, can require hours of delicate iterations during which the practitioner's arms remain essentially unsupported. The resulting repetitive stresses are known to be a cause of work-related shoulder and forearm trauma, including rotator cuff and carpal tunnel injuries. Fixed arm supports and supports that permit some lateral motion are known in the art and offer limited forearm and/or wrist relief. Problems arise, however, in connection with the high percentage of such tasks that protractedly require a larger—often much larger—range of horizontal and vertical motions.
Medical and scientific tasks may involve only lightweight hand-manipulated instruments and devices, but the stress on the practitioner can still be severe, due merely to the outstretched, unsupported weight of his or her arm(s) for the extended duration of these operations. Known ‘ergonomic’ shelf supports, including those on swing arms that provide a degree of lateral freedom, either restrict vertical motions or require awkward arm rotations to perform work above or below the nominal support height.
Common laboratory operations such as pipetting and ‘emulsion breaking’ however require repeated, unrestricted horizontal and vertical freedom of motion as various instruments are picked up and manipulated and set down. The ‘payload’ may indeed be trivial but the total weight of the operators cantilevered outstretched arm typically varies between three and ten pounds and self-supported can be exhausting over time, resulting in a disturbing number of injuries and lost workdays. Problems are compounded for activities utilizing even larger payloads than are used in laboratory tasks. There are countless such activities in numerous industries.
‘Pipetting’ and other medical and scientific operations, including countless surgical, dental and therapeutic procedures, could greatly benefit from having gravity effectively ‘negated’ for the practitioner by iso-elastic means that could also effortlessly parallel all the large and small motions of his or her human arm and wrist in three-dimensional space. Problems arise, however, in providing a comfortable, ergonomically appropriate connection between existing articulated support equipment and the dissimilarly articulated human arm, wrist, and/or hand.
The human arm is a biological miracle, but it is prone to fatigue, and ultimately to injuries, due to repetitive stress. What is needed is an agile supporting structure between it and an analogously jointed, lifting device, which can indefinitely preserve the unimpeded, multi-axis, angular agility of the human arm, forearm, wrist and hand. Further needed is a preferably lightweight, spring-powered, substantially frictionless mechanical arm, which uses no external power and, which fairly effortlessly follows the user's intended/hand arm positions while carrying the weight of his or her arm. It should preferably be highly iso-elastic (so it consistently lifts the selected amount of weight from the bottom to the top of its articulating range), and it should be of low inertial mass so it does not require much effort to move it along with rapidly up and down or lateral arm movements. It also preferably should include a ‘centering’ feature so it does not depart from the momentary selected position; and should be substantially frictionless to facilitate forearm rotations in pan, tilt and roll and spatial translations vertically, horizontally and towards/away-from the body of the user.
In summary, what is needed is a support apparatus that is spatially agile and can counter the weight of an outstretched human arm, wrist, and hand engaged in protracted tasks.